Interfacial engineering of Bi2Te3/Sb2Te3 heterojunction enables high–energy cathode for aluminum batteries

Rechargeable aluminum batteries (RABs) have been regarded as a low-cost and safe candidate for electrochemical energy storage. However, the high charge density of Al3+ causes its sluggish diffusion and the large size of AlCl4− renders the capacity of the cathode low. Here we propose heterostructured Bi2Te3/Sb2Te3 nanoflakes by interfacial engineering, constructing a heterojunction that induces a built-in electric field among the interface between two phases to realize rapid charge transfer, fast ion diffusion, and high capacity of cathode. Note that the operational mechanisms of heterostructured Bi2Te3/Sb2Te3 cathode are based on the reversible intercalation/deintercalation of Al3+ ions with the redox process between Bi3+ and Bi5+ upon discharge and charge. As expected, the heterostructured Bi2Te3/Sb2Te3 nanoflakes deliver superb Al-storage property and rate capability, which is among the best comprehensive performances of cathodes in RABs.